P0A0C: High Voltage System Interlock Circuit A Low
Do not keep driving
Have the vehicle recovered and do not attempt any work on it. This fault can mean the safety circuit that protects anyone working on the high-voltage system is compromised. If anybody has previously bridged or bypassed anything to make the car drive, tell the workshop before they start — it directly affects their safety.
What this code means
The interlock circuit reads below its valid range, normally a short to ground. Because the loop is monitored rather than merely switched, the module can tell a short from a clean open — and it treats a short with the same seriousness, because a shorted interlock is a defeated interlock.
That is the case worth naming plainly. A loop shorted to ground reports itself as intact whatever is disconnected, which removes the protection entirely: covers could be off and connectors open while the pack stays energised. Modules therefore refuse to close the contactors when they see this, rather than trusting a signal they know can no longer be trusted.
If a short has been introduced deliberately to make a car with an interlock fault drive, that is an extremely dangerous thing to have done and needs undoing by someone qualified before the vehicle is touched further.
Likely causes
Start here
- Wiring shorted to ground · specialist
- Damaged interlock wiring · specialist
- Corroded interlock connector pin · specialist
Less common
- Interlock circuit deliberately bypassed · specialist
- Water ingress into a high voltage connector · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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